Wu Bing, Jia Huichao, Yang Zhe, Shan Chao, Weng Jingxia, Xu Zhe, Pan Bingcai
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China E-mail:
Water Sci Technol. 2018 Dec;78(11):2404-2413. doi: 10.2166/wst.2018.526.
Direct use of zero-valent iron (ZVI) in reductive removal of selenate (Se(VI)) is inefficient due to the intrinsic passive layer of ZVI. Here we observed that ZVI pretreated with HO (P-ZVI-O) performs much better in Se(VI) removal from a mining effluent than other three modes of ZVI alone, acid washing ZVI (P-ZVI-A), and simultaneous addition of HO and ZVI (ZVI-O) as well. The P-ZVI-O exhibits exceptionally high Se(VI) removal at a low dosage, wide pH range, with Se dropping down from 93.5 mg/L to <0.4 μg/L after 7-h reaction. Interestingly, the initial pH (2-6) of the mining effluent exerted little influence on the final Se(VI) removal. HO/HCl pretreatment results in the formation of various reducing corrosion products (e.g. FeO, FeO and Fe), which greatly favors the efficient Se(VI) removal. In addition, surface-bound Fe ions participated in the reduction of Se(VI). Combined with the influence of Se valence as well as pH and Fe (whether dissolved or surface bound), it is deduced that the P-ZVI-O mode induced efficient Se(VI) removal via the adsorption-reduction and/or co-precipitation. This study demonstrates that HO/HCl pretreatment of ZVI is a very promising option to enhance the efficiency of reductive removal of Se(VI) from real effluents.
由于零价铁（ZVI）存在固有的钝化层，直接使用零价铁进行还原去除硒酸盐（Se(VI)）的效率较低。在此，我们观察到用HO预处理的ZVI（P-ZVI-O）在从采矿废水中去除Se(VI)方面比单独的其他三种ZVI模式、酸洗ZVI（P-ZVI-A）以及同时添加HO和ZVI（ZVI-O）表现得更好。P-ZVI-O在低剂量、宽pH范围内表现出极高的Se(VI)去除率，反应7小时后，Se从93.5 mg/L降至<0.4 μg/L。有趣的是，采矿废水的初始pH（2 - 6）对最终的Se(VI)去除影响很小。HO/HCl预处理导致形成各种还原腐蚀产物（如FeO、FeO和Fe），这极大地有利于高效去除Se(VI)。此外，表面结合的Fe离子参与了Se(VI)的还原。结合Se的价态以及pH和Fe（无论是溶解的还是表面结合的）的影响，推断P-ZVI-O模式通过吸附还原和/或共沉淀诱导了高效的Se(VI)去除。本研究表明，对ZVI进行HO/HCl预处理是提高从实际废水中还原去除Se(VI)效率的一个非常有前景的选择。
